UGANDA-SSUDAN-UNREST

Civilians who were evacuated from South Sudan arrive at the Entebbe International Airport in Uganda. (AFP/Getty Images / December 20, 2013)

WASHINGTON — Two U.S. military aircraft sent to assist in evacuations from war-torn South Sudan were hit by incoming fire Saturday, wounding four American service members and forcing the planes to abandon their mission, U.S. officials said.

One of the service members was in critical condition and one aircraft was badly damaged but still able to make it to an airfield in neighboring Uganda, the official said.

After the planes, tilt-rotor Ospreys flown by special operation troops, were hit, they turned around and headed for the airfield in Kampala, instead of landing in Bor, a rebel-held area in the state of Jonglei, the officials said.

The Pentagon said in a statement that the aircraft were sent to evacuate U.S. citizens from Bor, which has been the scene of intense ethnic fighting in recent days between Dinka and Nuer members.

"After receiving fire from the ground while approaching the site, the aircraft diverted to an airfield outside the country and aborted the mission," a statement from the Pentagon said.

The injured troops were receiving medical care, the statement said.

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